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Rollup merge of #95343 - dtolnay:literals, r=petrochenkov

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Reduce unnecessary escaping in proc_macro::Literal::character/string

I noticed that https://doc.rust-lang.org/proc_macro/struct.Literal.html#method.character is producing unreadable literals that make macro-expanded code unnecessarily hard to read. Since the proc macro server was using `escape_unicode()`, every char is escaped using `\u{…}` regardless of whether there is any need to do so. For example `Literal::character('=')` would previously produce `'\u{3d}'` which unnecessarily obscures the meaning when reading the macro-expanded code.

I've changed Literal::string also in this PR because `str`'s `Debug` impl is also smarter than just calling `escape_debug` on every char. For example `Literal::string("ferris's")` would previously produce `"ferris\'s"` but will now produce `"ferris's"`.
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Dylan DPC 2022-04-04 20:41:30 +02:00 • committed by GitHub
commit 2d1496a8f6
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3 changed files with 21 additions and 10 deletions
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16
compiler/rustc_expand/src/proc_macro_server.rs
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@ -658,16 +658,16 @@ impl server::Literal for Rustc<'_, '_> {
self.lit(token::Float, Symbol::intern(n), Some(sym::f64))
}
fn string(&mut self, string: &str) -> Self::Literal {
let mut escaped = String::new();
for ch in string.chars() {
escaped.extend(ch.escape_debug());
}
self.lit(token::Str, Symbol::intern(&escaped), None)
let quoted = format!("{:?}", string);
assert!(quoted.starts_with('"') && quoted.ends_with('"'));
let symbol = &quoted[1..quoted.len() - 1];
self.lit(token::Str, Symbol::intern(symbol), None)
}
fn character(&mut self, ch: char) -> Self::Literal {
let mut escaped = String::new();
escaped.extend(ch.escape_unicode());
self.lit(token::Char, Symbol::intern(&escaped), None)
let quoted = format!("{:?}", ch);
assert!(quoted.starts_with('\'') && quoted.ends_with('\''));
let symbol = &quoted[1..quoted.len() - 1];
self.lit(token::Char, Symbol::intern(symbol), None)
}
fn byte_string(&mut self, bytes: &[u8]) -> Self::Literal {
let string = bytes